Venezuela awoke to political turmoil Monday after Hugo Chavez's chosen successor, Nicolas Maduro, won the country’s presidential election by such a tight margin that his rival demanded a recount.

The country, already shaken by the death from cancer of its dominating leader, faces uncertainty after Maduro secured 50.7 percent of the votes in Sunday's election, compared with 49.1 percent for Henrique Capriles -- a difference of just 235,000 ballots.

"This is the most delicate moment in the history of 'Chavismo' since 2002," Javier Corrales, a U.S. political scientist and Venezuela expert at Amherst College in Massachusetts, told Reuters, referring to a brief coup against Chavez 11 years ago.

"With these results, the opposition might not concede easily, and Maduro will have a hard time demonstrating to the top leadership of Chavismo that he is a formidable leader."

Capriles refused to recognize the result and said his team had a list of more than 3,000 polling irregularities, Reuters reported.

"This struggle has not ended,” he said. "We are not going to recognize a result until each vote of Venezuelans is counted.”

"I didn't fight against a candidate today, but against the whole abuse of power," said Capriles, the 40-year-old governor of Miranda state. "Mr. Maduro, you were the loser. ... This system is collapsing, it's like a castle of sand -- touch it and it falls."

Officials said Maduro would be formally proclaimed winner at a ceremony and rally in downtown Caracas as early as Monday afternoon, Reuters reported.

For his part, Maduro said he would accept a full recount, even as he insisted his victory was clean and dedicated it to Chavez.

"We've had a fair, legal and constitutional triumph," Maduro told his victory rally. "To those who didn't vote for us, I call for unity."

One key Chavista leader expressed dismay over the outcome, The Associated Press reported. National Assembly President Diosdado Cabello, whom many consider Maduro's main rival within their movement, tweeted: "The results oblige us to make a profound self-criticism."

A modest but noisy crowd of Maduro supporters celebrated in Caracas’ Chacao neighborhood, waving flags and setting off fireworks.

A perception that Maduro has a weak mandate could prompt challenges from within the disparate ruling coalition that formed around Chavez, just as overstretched state finances force him to slow the very oil-funded largesse he staked his reputation on maintaining, Reuters said.

The OPEC nation's strong growth is seen by most private economists as dropping this year as the government pares back following hefty spending in 2012 that was a key driver of the economy and helped Chavez win re-election in October, Reuters reported.

Bill Richardson, the former governor of New Mexico, who was in Caracas as a representative of the Organization of American States, said in an interview that Maduro called him aside after a meeting of election observers on Saturday and asked him to carry a message, the NYT reported.

“He said, ‘We want to improve the relationship with the U.S., regularize the relationship,’” the newspaper quoted Richardson as saying.

Venezuela's electronic voting system is digital but generates a paper receipt for each vote, making a vote-by-vote recount possible, the AP said.